Of Meat and Mortality – Part 4: Harvard Study & Conclusion

Of Meat and Mortality – Part 4 is a review of the results from a study combining the data on 37,698 men from of the Health Professionals Follow-up Study (1986-2008) and 83,644 women from the Nurses’ Health Study (1980-2008). This study was conducted by the Harvard School of Public Health and published one year ago (1).

There were some benefits this study had over the others. The inclusion criteria was a bit more stringent (you could not have had angina or a heart attack compared to just not having had a heart attack in the other studies (2)), the follow-up was long (22-28 years, the other studies either had much shorter follow-up or much less people to follow), and they assessed the diet regularly over time. Since they were all health professionals, it minimized income and lifestyle disparities.

The intake amount categories were divided into fifths, with the largest being about 2 servings per day for both men and women (unprocessed plus processed red meat).

They only reported two models: age-adjusted-only and multivariate. Once again, their multivariate model contained adjustments that likely interacted with red meat’s effect on mortality: history of diabetes, hypertension, or hypercholesterolemia, and energy intake. Even so, unprocessed red meat was associated with increased mortality (1.36, 1.25-1.47) as was processed red meat (1.27, 1.18-1.38). When men and women were separated, the findings held. The results also held for cardiovascular disease (no surprise) and for cancer (not a huge surprise, but the association was weaker).

The authors said:

“Compared with red meat, other dietary components, such as fish, poultry, nuts, legumes, low-fat dairy products, and whole grains, were associated with lower risk. These results indicate that replacement of red meat with alternative healthy dietary components may lower the mortality risk.”

Conclusion Of Meat and Mortality

Let’s sum up the 4 studies:

EPIC (3) – Large study, highest red meat intake category was about 2 servings per day, processed red meat was strongly associated with mortality, unprocessed was associated with mortality in the model that did not adjust for body mass index (BMI), removing first 2 years of follow-up didn’t change results.

NHANES (4) – Small but long study, highest intake category was roughly 1.5 times per day, unprocessed and processed meat was strongly associated with mortality until results were adjusted for many variables which could be influenced by red meat, strong reason to believe people in the lowest intake category had cut down on red meat due to previous disease.

Shanghai (5) – Only “red” meat was pork and very little processed meat, highest intake category was about 1 serving per day, red meat intake was positively associated with total mortality among men but not among women, results were likely adjusted for conditions that could be affected by red meat intake.

Harvard (1) – Highest quality study, largest intake category was 2 servings of red meat per day, red and processed meat strongly associated with mortality in both men and women even after adjusting for many factors that could be influenced by red meat intake.

My conclusion is that eating two servings of red meat per day mostly likely increases the risk of early death over eating a half serving or less, and especially if it’s processed. To be more certain, a model is needed that does not adjust for any of the factors that red meat likely influences while adjusting for all those that it doesn’t.

That said, it’s not a slam dunk and I’d rather people were eating cows and pigs than birds (because it takes so many more birds to produce the same amount of meat) so I don’t necessarily consider this good news.

My vote is for people to replace the red meat in their diet with legumes and nuts!

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Reference

1. Pan A, Sun Q, Bernstein AM, Schulze MB, Manson JE, Stampfer MJ, Willett WC, Hu FB. Red meat consumption and mortality: results from 2 prospective cohort studies. Arch Intern Med. 2012 Apr 9;172(7):555-63. | link

2. van Dam RM, Willett WC, Rimm EB, Stampfer MJ, Hu FB. Dietary fat and meat intake in relation to risk of type 2 diabetes in men. Diabetes Care. 2002 Mar;25(3):417-24. | link

3. Rohrmann S, et al. Meat consumption and mortality – results from the European Prospective Investigation into Cancer and Nutrition. BMC Med. 2013 Mar 7;11:63. | link

4. Kappeler R, Eichholzer M, Rohrmann S. Meat consumption and diet quality and mortality in NHANES III. Eur J Clin Nutr. 2013 Mar 13. | link

5. Takata Y, Shu X-O, Gao Y-T, Li H, Zhang X, et al.Red Meat and Poultry Intakes and Risk of Total and Cause-Specific Mortality: Results from Cohort Studies of Chinese Adults in Shanghai. PLoS ONE. 2013 Feb 18;8(2):e56963. doi:10.1371/journal.pone.0056963 | link

8 Responses to “Of Meat and Mortality – Part 4: Harvard Study & Conclusion”

  1. Bertrand Russell Says:

    >My vote is for people to replace the red meat in their diet with legumes and nuts!

    True dat. If only it worked that way. As Ginny points out:

    http://www.theveganrd.com/2011/08/bad-news-for-red-meat-is-bad-news-for-chickens.html

    :-(

  2. AmyLu Says:

    What is the reason you would rather see people eat mammals than birds?

  3. Jack Norris RD Says:

    AmyLu,

    By “mammals” I meant typical farmed mammals like cows and pigs, and that’s because it takes so many more chickens to equal one cow or pig which results in a lot more animals suffering. When it comes to smaller mammals, then I wouldn’t have a preference — would much rather see people eat legumes instead.

  4. Jack Norris RD Says:

    I changed the post to reflect what I meant about preferring people to eat mammals.

  5. Mark Says:

    Jack,

    I’ve always struggled with the notion that the “quantity” of suffering is equal to the number of animals killed, or that reducing suffering always trumps other reasons for not eating animals. By this notion we should be farming elephants and maybe even humpback whales because they provide more “meat” per brain (maybe a good idea for one of PETA’s off the wall campaigns :-)). Conversely vegans should be adamantly against others eating insects as a protein source because of the larger numbers of insects required. But I suspect most veg*ns don’t believe this. Given that a cow has a larger brain (suffers more?) and is much less efficient at converting feed to muscle/fat than a chicken, does it make sense to argue against transitioning from cows to chickens for food in the grand scheme of things?

    Of course I whole heartedly agree with your sentiment of switching to legumes, but then this is essentially an argument for vegetarianism, and we know that folks aren’t always ready for that.

    So faced with a stark choice – eating beef or chicken (or insects!) at every meal – what is better for animals, the environment and human health? Would love to hear your thoughts on this.

    Tx!

  6. Jack Norris RD Says:

    Mark,

    My thoughts on this are not necessarily very informed as it’s been years since I closely studied the research on the capacity for suffering in cows and chickens. At the time, there was not a whole lot to be found. Since then, I have paid cursory attention to the research (there has been some on chickens and possibly even more on fish). My sense is that birds suffer enough to put moral concerns regarding their suffering on par with mammals.

    I tend to think that insects (and other “bugs”) are not conscious of suffering and would be thrilled if people started eating them instead of mammals and birds.

    But, again, plant foods would be my preferred source of food for humans.

  7. 번데기 Says:

    >…and would be thrilled if people started eating them…
    Oh, you mean “I”, not “insects”.

  8. Jack Norris RD Says:

    번데기,

    Good one!

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